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(No Model.)

D. W. DE FOREST. Electric Condenser.

No. 239,370. Patented March 29,1881.

L WMM/5m NJETERS, PH0T0-L|YHOGRAPHER, wAsHlNaTON. D C

' UNITED STATES DAVID IV. DE FOREST, OF BROOKLYN, ASSIGNOB TO WILLIAM BUCHANAN PATENT OFFICE.

OF NEV YORK, N. Y.

ELECTRIC CONDENSER.

SPECIFICATION forming part of Letters Patent No. 239,370, dated March 29, 1881.

Application illed January 29, 1881.

To all whom it may concern:

Be it known that I, DAVID W. DE FOREST, of Brooklyn, in the county ot' Kings and State of New York, have invented a new and uset'ul ImprovementinElectric Oondensers, of which the following is a specification.

My invention relates to electric condensers, and is au improvement on my application for Letters Patent for the same purpose Iiled No- 1o vember 17, 1880.

The objects of my present invention are, first, to produce an apparatus which is composed principally ot' but two long sheets of conducting material wound or folded alternately upon each other, with an intervening non-conducting or insulating' substance; and, second, to insure the condenser from losing` its charge by the action of moisture or other outside causes.

2o In the accompanying drawings, which form part of this specification, Figure l is a horizontal sectional view. Fig. 2 is a vertical longitudinal sectional view, and Fig. 3 represents a horizont-al sectional view of a condenser in a modied form.

Similar letters refer to similar parts throughout the several views.

In the construction ot' my condensers I use for conductors ofthe positive and negative electricity two long thin sheets of a well-prepared good-conducting material, such as tinfoil, having a certain uniform width throughout. rIhe length and width of the sheets depend on the desired capacity of the condenser. For the insulation I employ somewhat longer and wider sheets of a non-conducting material, such as paraftined paper, specially prepared gutta-percha, or other equally good non-conducti n g substance. The inner ends ofthe conductors are fastened, with their entire width, to the respective positive or negative pole by winding the said ends once or twice around the poles, and when the winding or folding of all the sheets has been accomplished in the 4 5 manner hereinafter more fully described, the

outer ends of the conductors are sealed up by the'outer ends ot' the insulating` material. In covering the width of the conductors with the width ofthe insulators, it will be noticed that 5o the greater width of the latter leaves a mar- (No model.)

giu (generally about one inch) on the upper and lower sides, which prevents the positive and negative conductors from forming a connection at these places. (See Fig. 2.)

In the drawings the heavy black lines represent the sheets of conducting material, and of which c is the conductor for the positive, and b the conductor i'or the negative, electricity.

A is a positive, and B is a negative, pole, placed a given distance apart, and connected 6c in any desired way to sources of electricity.

rIhe construction ot' my condensers is as follows: The inner end of thc positive conductor a is wound once or twice around the positive pole A, and then covered on its outside by a sheet of insulating` material, af, and the inner end of the negative conductor I) is wrapped once or twice around the negative pole B, and covered hy a sheet of non-conducting material 1;. The materials aand a' are then passed 7o over to and wound on the sheets b and b in such a ina-nner that sheet a covers the sheet b', (seeFig.l,) and the sheets b and b are passed over to and wound 011 the sheets a and a' on the pole A, so that conductor blies next to the non-conductora', while theinsulating-sheet b covers the outside of conductor b. The several sheets of conducting and non-conducting material are now wound simultaneously upon each other in the manner just described until 8o the outer ends ot' the conductors a and Z1 are reached. Now, as the insulating-sheets a and b are somewhat longer than the conductors a and b, the outer ends ot' a and D are lapped over the outer ends of the conductors a and I), and thereby sealed, as may be plainly seen in Fig. l. rIhe inner ends ofthe insulating-sheets a and b are placed against the inner sides of the conductors a and b when they are passed as first layers from one pole to the other. 9o

To prevent moisture or other good outside conductor of electricity to disturb the condenser, I place the latter in boXD of non-conducting material, and till the space not occupied by the condenser with a non-conducting substance, G. For this purpose I prefer to use melted pai-affine, which, after being' poured in the box D, is allowed to cool and become hard. In this way not only the unoccupied space in the box, but also the margins on the roo upper and under sides of the condenser become illed up by the melted substance, whereby the greatest insulation of the conductors at their edges is insured. (See Fig. 2.)

The ends ofthe poles A and B are allowed to pass through the lid and bottom ofthe box D, Where they may be connected to some source of electricity in any desired way.

In Fig. Sis a condenser represented in which the inner ends of the conductors a and b are fastened to the respective poles A and B in the same manner as described before in reference to Figs. land 2; but instead of winding the different sheets of conducting and non-conducting material, they are folded alternately upon each other, so that one or more sheets of insulating material intervene between the positive and negative conductors, and also cover completely the outsides. as may be seen in Fig. 3. The outer ends of the conductors a and b are sealed by lapping the outer ends of the insulators a and b over them. The soconstrueted condenser may be placed in abox or other suitable receptacle, and the remaining space between the condenser and the box and the space on the upper and under margins lled with a non-conducting substance in the same way and manner as described before in regard to Figs. 1 and 2.

It will be observed that t-he outer ends of the conductors a and b have no connection with the outside whatever.

l. In an electric condenser, the conductors a and b, each having its inner end wrapped once or twice around its respective pole A or B, and wound or folded in conjunction with the insulating materials a an d b', alternately7 upon each other, as described, and having the outer ends of the conductors a and b sealed up by the outer ends of the non-conductin g materials a and b. as described, and for the purpose as specied.

2. In an electric condenser, the conductors a and b, the insulating materials a and b', the poles A and B, all arranged as described, in combination with the insulating substance G, as and for the purpose spccied.

- DAVID W. DE FOREST.

Witnesses:

THEO. G. Hos'rnn, Gnus. R. CLARKE. 

